In an enormous political upset, House Majority Leader Eric Cantor lost his Republican primary in Virginia’s seventh congressional district Tuesday night to Dave Brat, an economics and ethics professor at Randolph-Macon College in Ashland, Virginia, and political unknown.

According to the Associated Press, with 86.1 percent of precincts reporting Brat won with 55.8 percent of the vote to Cantor's 44.2 percent. Cantor became the first person in American history to lose his party's primary while holding the position of House majority leader, according to Roll Call, the Capitol Hill newspaper.

Brat’s bid was widely seen as a long-shot, improbable campaign to unseat the possible heir to Speaker John Boehner. Cantor has long been seen as the member of Republican leadership friendliest to the tea party, but it’s possible his portrayal as being open to immigration reform is what hurt him in this campaign.

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Eric Cantor Loses Primary in Shocking Upset

“I’m sure [immigration] contributed to it, but I think being a member of House leadership contributed to it too,” said Kyle Kondik, managing editor of Sabato’s Crystal Ball at the University of Virginia Center for Politics.

Last week, in a Richmond Times Dispatch op-ed, Brat called Cantor the "No. 1 cheerleader in Congress for [immigration] amnesty.”

Cantor spoke to his supporters gathered at what they thought would be a victory party , saying he knows there are “a lot of long faces here tonight and, it's disappointing, sure, but I believe in this country, I believe there is opportunity around the next corner for all of us.”

“So I look forward to continuing to fight that fight with all of you for the things we believe in for the conservative cause because those solutions of ours are the answers to the problems that so many people are facing today,” Cantor said, not making it clear whether he was conceding or if he would wage a write-in campaign.

Brat, 49, though poorly funded, did have some high-profile conservatives behind him with both Ann Coulter and Laura Ingraham backing his bid. Cantor spent over $5 million in this race while Brat spent just over $100,000.

In an interview with ABC News last month, Brat accused Cantor of losing touch with his constituents and “veering from the Republican creed.”

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“This isn’t a personal race. I’m not running against Eric,” Brat stressed. “I’m just running on the founding principles that Adam Smith and free markets – they made us the greatest nation on the Earth. All right? It’s no mystery. Our rights, tradition, along with free markets and the Judeo-Christian tradition all together made us the greatest nation on the face of the Earth. I think we’re veering off course a little bit there and I want to get us back on that course that brought us to greatness.”

This isn’t the first primary challenger Cantor, 51, has faced. He smoked primary challenger Floyd Bayne in 2012 by nearly 60 percentage points before cruising to a 17-point victory in the general election. Cantor was first elected to the House in 2001 and has served as majority leader since 2011.

In May, Cantor’s senior strategist Ray Allen told ABC they didn't see “[Brat] getting a great deal of traction.”

This win also upends the conventional wisdom that the tea party was losing this primary cycle.

“The statement from the grassroots could not be any clearer. It doesn’t matter what office you hold or how powerful you are. If you lose touch with activists on the ground, then your seat is in danger,” FreedomWorks President Matt Kibbe said in a statement.

According to Kondik at the University of Virginia Center for Politics, since World War II “only two percent of House members who sought another term have lost re-nomination.”

Although it is far from clear if Cantor would wage a write-in bid, Kondik says it “appears that he could run as a write-in if he wanted to. It would be his only way. It seems to be a legal possibility.”

In 2010, Alaska Sen. Lisa Murkowski waged a successful write-in campaign against Joe Miller when she too lost a shocking primary. Murkowski actually conceded to Miller before changing her mind and waging the write-in effort. It is hard to compare anything to the unique Alaska electorate, but both Murkowski and Cantor have nearly universal name recognition in their respective states, and they both are able to raise money.

“There is only one other member of the House that lost re-nomination this year,” Kondik noted. “(Texas’) Ralph Hall. It’s not like we had a flood of these upsets and I don’t expect there to be a flood afterwards. This is a weird fluky event.”

In a statement, Democratic National Committee Chair Debbie Wasserman Schultz said Cantor’s loss, “settles the debate once and for all - the Tea Party has taken control of the Republican Party. Period.”

“When Eric Cantor, who time and again has blocked common-sense legislation to grow the middle class, can't earn the Republican nomination, it's clear the GOP has redefined 'far right.' Democrats on the other hand have nominated a mainstream candidate who will proudly represent this district and I look forward to his victory in November,” Schultz said in a statement.